The present invention is directed to a self-sealing coffee pot.
Coffee is a ubiquitous beverage; it is served in homes, restaurants, and workplaces. Many devices for brewing coffee have been invented; the majority of these devices brew a batch of coffee and then store it for consumption within a short time. Some coffee brewing devices store coffee in a removable container, or coffee pot, that rests in or on a storage location within the brewing device. A coffee pot generally holds 6-10 servings of coffee; it has a handle for carrying the coffee pot without contacting hot coffee or hot parts of the coffee pot; it has an upward-opening mouth to permit the coffee brewing device to dispense brewed coffee into the pot and to permit serving coffee from the coffee pot by pouring.
One requirement of serving coffee is that it must be served hot (150-170.degree. F.), at a temperature close to its brewing temperature. To keep the coffee in the coffee pot at the proper serving temperature, brewing devices often have electric heating elements that continuously heat the bottom of the coffee pot to maintain the coffee at an acceptable serving temperature.
This continuous heat input maintains coffee at the proper serving temperature but also has the undesirable side effect of evaporating the water used to brew the coffee. As the water evaporates, the coffee changes. The first noticeable change is a degradation of the flavor. As more water evaporates or as coffee is served from the coffee pot, the volume of coffee in the pot decreases. Most coffee brewing devices have a constant heat input to the heating elements, thus the decrease in coffee volume causes an increase in specific heat input (heat per unit volume) causing the coffee temperature to rise and increase its rate of evaporation. This increased temperature causes the coffee to develop a burned taste; at this point the coffee is no longer suitable for consumption. If the coffee pot remains on the heating element, the evaporation rate increases with the increasing temperature until the coffee evaporates completely, leaving a burnt deposit in the bottom of the coffee pot. This deposit is difficult to remove and often renders the coffee pot unusable because the sediment cannot be removed completely or leaves an undesirable odor in the coffee pot permanently.
There have been previous attempts to remedy the problem of evaporation coffee in brewing devices. U.S. Pat. No. 3,974,758 to Stone discloses a device to reduce this effect in a coffee brewing device that does not have a removable coffee pot. The Stone device does not allow for the dispensing of coffee into the coffee storage container without the removal of component 18. This represent complicates coffee brewing as the device must be removed prior to dispensing coffee into the coffee pot and re-installed after brewing is complete, a process that can take from two to ten minutes.
U.S. Pat. No. 4,482,083 to Beck discloses a coffee saver device addressing the same concerns; however, that device does not provide a substantially complete seal as there is a hole 48 in element 46 which allows a significant, continuous release of coffee vapors. Additionally, the funnel member sloping surfaces 50 have a substantial contact area with the annular flange 40. This extensive contact area is wetted by the dispensing of coffee into the device and then tends to remain wet as evaporated water from the coffee condenses on the device. These wetted components tend to adhere one to the other because of the surface tension created by the condensed coffee vapor; this makes controlling the coffee during pouring difficult, as the funnel member will adhere to the annular flange until the adhesive force holding the funnel member to the annular flange is broken by the funnel member's weight and possibly the coffee as the coffee pot is tipped. The sleeve also obscures visual observation of the funnel member 46 movement, making the serving of coffee difficult to control because of unpredictable funnel member movement. Proper sanitation of this device is also difficult because there are many wetted surfaces some of which are inaccessible for cleaning and visual observation.
A number of patents disclose liquid traps for reducing vapor release from coffee containers. For example U.S. Pat. No. 4,638,929 to Stone discloses such a device. The device presents difficulties in serving coffee as it restricts the flow of coffee during serving as the coffee must pass through a complex pathway with a small cross-sectional area. The device also does not permit pouring all of the contents of the coffee pot, as some coffee will be trapped above the divider wall 58, even if the coffee pot is inverted to the fully upside down position. This device is relatively complicated to manufacture, requiring complex, three-dimensional components that must fit very closely for the device to function properly. The device also has inaccessible wetted surfaces making proper sanitation difficult.